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Re: [Qemu-trivial] [PATCH] vmdk: Fix cylinders number during convert
From: |
Michael Tokarev |
Subject: |
Re: [Qemu-trivial] [PATCH] vmdk: Fix cylinders number during convert |
Date: |
Thu, 23 Oct 2014 10:55:18 +0400 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Icedove/24.8.1 |
On 10/22/2014 05:25 PM, Arthur Gautier wrote:
> We can not rely on int cast to get a correct number of cylinders. The
> cylinders information was wrong in 49.9999% of cases.
>
> This ensures the cylinders always gets the ceiling value.
Good thing, especially the good probability :), and also a good patch
which comes with a test.
But I wonder if anything can break this way? Migration, windows guest
being unable to find its partitions, something else?
And more. What-if our drive size in cylinders will be larger than
the size in bytes? The proposed div_round_up() will increase number
of cylinders, so size in CHS will be larger than size in bytes. Maybe
there was a reason why originally the size in cylinders was calculated
by truncating extra fractional part? What-if guest will try to access
the very last CHS which is incomplete?
Thanks,
/mjt
> Reviewed-by: William Dauchy <address@hidden>
> Signed-off-by: Arthur Gautier <address@hidden>
> ---
> block/vmdk.c | 4 +--
> tests/qemu-iotests/106 | 67
> ++++++++++++++++++++++++++++++++++++++++++++++
> tests/qemu-iotests/106.out | 5 ++++
> tests/qemu-iotests/group | 1 +
> 4 files changed, 75 insertions(+), 2 deletions(-)
> create mode 100755 tests/qemu-iotests/106
> create mode 100644 tests/qemu-iotests/106.out
>
> diff --git a/block/vmdk.c b/block/vmdk.c
> index 4ae6c75..c22a6c6 100644
> --- a/block/vmdk.c
> +++ b/block/vmdk.c
> @@ -1928,8 +1928,8 @@ static int vmdk_create(const char *filename, QemuOpts
> *opts, Error **errp)
> parent_desc_line,
> ext_desc_lines->str,
> (flags & BLOCK_FLAG_COMPAT6 ? 6 : 4),
> - total_size /
> - (int64_t)(63 * number_heads *
> BDRV_SECTOR_SIZE),
> + DIV_ROUND_UP(total_size,
> + (int64_t)(63 * number_heads *
> BDRV_SECTOR_SIZE)),
> number_heads,
> adapter_type);
> desc_len = strlen(desc);
[]
- [Qemu-trivial] [PATCH] vmdk: Fix cylinders number during convert, Arthur Gautier, 2014/10/22
- Re: [Qemu-trivial] [PATCH] vmdk: Fix cylinders number during convert,
Michael Tokarev <=
- Re: [Qemu-trivial] [Qemu-devel] [PATCH] vmdk: Fix cylinders number during convert, Markus Armbruster, 2014/10/23
- Re: [Qemu-trivial] [Qemu-devel] [PATCH] vmdk: Fix cylinders number during convert, Stefan Hajnoczi, 2014/10/28
- Re: [Qemu-trivial] [Qemu-devel] [PATCH] vmdk: Fix cylinders number during convert, Fam Zheng, 2014/10/28
- Re: [Qemu-trivial] [Qemu-devel] [PATCH] vmdk: Fix cylinders number during convert, Arthur Gautier, 2014/10/30
- Re: [Qemu-trivial] [Qemu-devel] [PATCH] vmdk: Fix cylinders number during convert, Fam Zheng, 2014/10/30
- Re: [Qemu-trivial] [Qemu-devel] [PATCH] vmdk: Fix cylinders number during convert, Arthur Gautier, 2014/10/31
- Re: [Qemu-trivial] [Qemu-devel] [PATCH] vmdk: Fix cylinders number during convert, Fam Zheng, 2014/10/31